It could be bacterial, or it could be fungal. I'd say a biopsy is probably necessary or you would just be guessing on what to treat it with and wasting time while it's getting worse and spreading.


"Fungal Infections: A number of fungal organisms can cause superficial and deeper infections of snakes. Most of these infections involve the skin and respiratory system. Fungal infections of the eyes are most likely to occur in snakes housed in damp, contaminated environments. Ringworm fungi that usually infect people, pets and livestock have also caused skin infections of snakes. Snakes must be housed in scrupulously clean and dry enclosures. The flooring must be easy to clean and should not be of a material that encourages fungal (mold) growth (see section on Housing). A veterinarian must examine Snakes exhibiting problems with their skin and/or eyes as soon as possible. A microbial culture and a skin biopsy may be necessary to obtain a diagnosis. Treatment of fungal diseases involves use of topical and systemic (oral and/or injectable) antifungal agents. Prevention of fungal disease involves correcting underlying problems with husbandry"